Process for oxidizing ammonium sulfite to ammonium sulfate.



srarne AEN ()FFICE.

HEINRICH DANNEEL AND EMIL KUHN, 0F BASEL. SWITZERLAND, ASSIGNORS TO ELEKTRIZITATSXVERK LONZA, 0F GAMPEL, SWITZERLAND.

PROCESS FOR OXIDIZING AMM C'NIUM SULFITE TO AMMONIUM SULFATE.

No Drawing.

To all when: it may concern.-

Be it known that we, llnlxmou [)xxxnun, chemist. a subject of the (ll-and Duke of Mecklenburg- Schwerin, aml resident of Basel, Switzerland and Earn, Kenn, chemist, a citizen of the Swiss Republic, and resident of Basel, Switzerland. have invented Processes for ()xidizing Ammonium Sulfite t0 Ammonium Sulfate, of which the following is a full, clear, and exact spccitication.

It is known that alkali sultites, including ammonium sultite, can be oxidized by oxygen or air to sulfates. When air is used the oxidation proceeds very slowly, and as ammonium sulfite is fumlanientally hydrolyzed in aqueous solution, the nitrogen of the air carries away ammonia. ()nce oxidation to sulfate has occurred, however, loss of ammonia is no longer to be feared. since the sulfate suffers little hydrolysis. It is therefore advantageous that the oxidation should be as rapid as possible.

By this invention a sparingly soluble sulfate, such as calcium sulfate, can act as an oxygen-carrier for the oxidation in question. Thus, when ammonium sultite solution is passed over gypsum, owing to the fact that calcium sulfite is more sparingly soluble than the sulfate, there happens immediately a double decomposition according to the equation- (NHQ SO +CaSO,: una so oaso The oxidation may now proceed slowly without danger of loss.

Butwe have found that calcium sultito can be oxidized far more easily and quickly to sulfate than ammonium sulfite can, so that the addition of calcium sulfate presents a double advantage, first the immediate suppression of the hydrolyzed (NHQ SO that is to say the prevention of loss of. ammonia,

Specification of Letters Patent.

Application filed July 21,

Patented July 30, 1918.

1917. Serial No. 182040;.

and secondly. the :u-eeleration of the process of oxidation, that is to say a saving of time.

l rom the foregoing it is obvious that when an anunonimn sulfite solution is passed over gvpsum contained in a chamher. while air is simultaneously introduced in the said chamber. the ammonium sulfite will be immediately transformed into ammonium sulfate according to the above indicated equation, while the calcium sulfite simultam-ously formed according to the said equation will also immediately be reoxidized by the oxygen of the air to calcium sulfate according to the equation CaSQ f-O CaSO so that only a little quantity of gypsum will be necessary to insure the transformation of an unlimited quantity of ammonium sulfite into :mnnonium sulfate, the same quantity of gypsum acting continually as an oxygen carrier. that is to say for transmitting the oxygen from the air unto the ammonium sultite.

What we claim is:

1. A process for oxidizing ammonium su1- tite to ammonium sulfate by air, wherein the oxidation is conducted in presence of a sparingly soluble sulfate.

2. A process for oxidizing ammonium sultite to ammonium sulfate by air, wherein the oxidation is conducted in presence of calcium sulfate.

In witness whereof we have hereunto signed our names this 15th day of March, 1917, in the presence of two subscribing witnesses.

vIIEINRICI'I DAN NEEL. EMIL KUHN. Witnesses:

ANNA Amnurr, A MAN n Rrr'rnn. 

